The invention relates to an IC card system which is comprised of an IC card and an IC card terminal.
IC cards possess internal data processing functions (CPU functions) and memory functions. Because of the CPU functions, they have the characteristics of accurate verification of the holder and the card itself and so forth, as well as simplified prevention against data reading, writing, and alteration. Moreover, they can be designed to have a large memory capacity. They have therefore been anticipated not only as a substitute for conventional magnetic cards but also for new applications.
For example, the above-mentioned IC card can be used as a coupon ticket and the procedure for use of the card in this case will be described below. First, the issuer stores the amount of money or number of times the card can be used in the memory section of the IC card using a specific code number and keyword not known to others. The user purchasing this card inserts it into a terminal controlled by the issuer each time he uses the card, and the number of times or amount of money used is subtracted. Additionally, if an electrically erasable and programmable memory (EEPROM) is used for the card memory, when the remaining amount of money or number of transactions left reaches zero, the user can bring the card to the issuer and by paying money, the usable amount of money or number of times can be stored in the card again. This allows the same card to be used as a coupon ticket any number of times. This has the benefit of allowing the user to purchase only the required number of times, unlike conventional coupon tickets which had a fixed number of times.
Furthermore, because the card itself possesses calculation functions it is easily possible to use the card for multiple purposes, for example for bus, trains, etc., and to make price settlement (coupon ticket settlement). In addition, cards issued by different issuers can be used interchangeably and settlement can be made easily by use of the CPU and memory functions of the card.
Additionally in these cases, forgery of these cards or malicious data writing to the cards is extremely difficult. The cards are therefore superior to magnetic cards in this regard.
However, when the cards are used as coupon tickets in the above example, there is the drawback that the remaining amount of money or number of times cannot be easily determined by having a look at it. This is preventing the use of IC cards for coupon tickets, for example.